Cytosolic DNA initiates a vicious circle of aging-related endothelial inflammation and mitochondrial dysfunction via STING: the inhibitory effect of Cilostazol.

Endothelial senescence, aging-related inflammation, and mitochondrial dysfunction are prominent features of vascular aging and contribute to the development of aging-associated vascular disease. Accumulating evidence indicates that DNA damage occurs in aging vascular cells, especially in endothelial cells (ECs). However, the mechanism of EC senescence has not been completely elucidated, and so far, there is no specific drug in the clinic to treat EC senescence and vascular aging. Here we show that various aging stimuli induce nuclear DNA and mitochondrial damage in ECs, thus facilitating the release of cytoplasmic free DNA (cfDNA), which activates the DNA-sensing adapter protein STING. STING activation led to a senescence-associated secretory phenotype (SASP), thereby releasing pro-aging cytokines and cfDNA to further exacerbate mitochondrial damage and EC senescence, thus forming a vicious circle, all of which can be suppressed by STING knockdown or inhibition. Using next-generation RNA sequencing, we demonstrate that STING activation stimulates, whereas STING inhibition disrupts pathways associated with cell senescence and SASP. In vivo studies unravel that endothelial-specific Sting deficiency alleviates aging-related endothelial inflammation and mitochondrial dysfunction and prevents the development of atherosclerosis in mice. By screening FDA-approved vasoprotective drugs, we identified Cilostazol as a new STING inhibitor that attenuates aging-related endothelial inflammation both in vitro and in vivo. We demonstrated that Cilostazol significantly inhibited STING translocation from the ER to the Golgi apparatus during STING activation by targeting S162 and S243 residues of STING. These results disclose the deleterious effects of a cfDNA-STING-SASP-cfDNA vicious circle on EC senescence and atherogenesis and suggest that the STING pathway is a promising therapeutic target for vascular aging-related diseases. A proposed model illustrates the central role of STING in mediating a vicious circle of cfDNA-STING-SASP-cfDNA to aggravate age-related endothelial inflammation and mitochondrial damage.

GOLPH3/CKAP4 promotes metastasis and tumorigenicity by enhancing the secretion of exosomal WNT3A in non-small-cell lung cancer.

Cancer metastasis is the main cause of mortality associated with non-small-cell lung cancer (NSCLC), accounting for up to 70% of deaths among patients. The mechanisms underlying distal metastasis remain largely unknown. Golgi phosphoprotein 3 (GOLPH3) correlates negatively with overall survival in multiple tumors. In this study, we evaluated the function of GOLPH3 in NSCLC distal metastasis. GOLPH3 was expressed at high levels in samples from patients with NSCLC and was positively associated with clinicopathologic characteristics including clinical stage (P < 0.001), T (P = 0.001), N (P = 0.007), and M (P = 0.001) classification. Functionally, Transwell and wound-healing assays suggested that GOLPH3 overexpression enhances NSCLC cell migration and invasion abilities. Tumor-sphere formation and flow cytometry assays demonstrated that GOLPH3 overexpression enhances a stem cell-like phenotype of NSCLC cells. Metastasis models established by tail vein and intracardiac injection confirmed the pro-metastatic function of GOLPH3 in vivo. A subcutaneous tumor formation model confirmed that GOLPH3 overexpression increased the tumorigenicity of NSCLC cells. Mechanistically, gene set enrichment analysis revealed a positive association of GOLPH3 mRNA expression with WNT-activated gene signatures. Luciferase-reporter and nuclear extract assays showed that GOLPH3 overexpression enhances metastasis and tumorigenicity through activation of the WNT/ß-catenin pathway. Immunoprecipitation-mass spectrometry and gene ontology analysis demonstrated that GOLPH3 interacts with cytoskeleton-associated protein 4 (CKAP4) in exosome-mediated distal metastasis. We found that GOLPH3 decreased the amount of plasma membrane-localized CKAP4 and increased the amount of exosome-localized CKAP4 to promote the formation of CKAP4-containing exosomes. Furthermore, we demonstrated that CKAP4 binds exosomal WNT3A to enhance its secretion. Therefore, the GOLPH3/CKAP4 axis plays a crucial role in promoting exosomal-WNT3A secretion to enhance and maintain the stem-like phenotype and metastasis in NSCLC, thus indicating the therapeutic potential of GOLPH3 in patients with NSCLC metastasis.